Force CMake version 3.21.0+ for the FFMPEG extension

Issue: google/ExoPlayer#9933
#minor-release
PiperOrigin-RevId: 434449816

extensions/ffmpeg/build.gradle

@@ -17,7 +17,8 @@ apply from: "$gradle.ext.exoplayerSettingsDir/common_library_config.gradle"
 // failures if ffmpeg hasn't been built according to the README instructions.
 // failures if ffmpeg hasn't been built according to the README instructions.
 if (project.file('src/main/jni/ffmpeg').exists()) {
 if (project.file('src/main/jni/ffmpeg').exists()) {
     android.externalNativeBuild.cmake.path = 'src/main/jni/CMakeLists.txt'
     android.externalNativeBuild.cmake.path = 'src/main/jni/CMakeLists.txt'
-    android.externalNativeBuild.cmake.version = '3.7.1+'
+    // Should match cmake_minimum_required.
+    android.externalNativeBuild.cmake.version = '3.21.0+'
 }
 }
 
 
 dependencies {
 dependencies {

extensions/ffmpeg/src/main/jni/CMakeLists.txt

@@ -14,7 +14,7 @@
 # limitations under the License.
 # limitations under the License.
 #
 #
 
 
-cmake_minimum_required(VERSION 3.7.1 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.21.0 FATAL_ERROR)
 
 
 # Enable C++11 features.
 # Enable C++11 features.
 set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_CXX_STANDARD 11)